An existing window covering driving device generally comprises a motor and a motor control segment; the motor control segment is divided into two kinds, mechanical control and circuit control; the structure of a mechanical control segment is comparatively complicated, which requires a quite fine manufacturing technology, and is easy to wear, so, more and more manufacturers use a circuit to control the operating of the drive motor of a window covering. The control circuit of an existing window covering drive motor generally comprises a microprocessor, a control wire, a control button, and a switching circuit; the drive motor is connected to a drive power supply via the switching circuit; the switching circuit is connected to the microprocessor; the control button is connected to the microprocessor via the control wire; the control button can separately control the motor to run in clockwise or counterclockwise direction This kind of window covering drive motor generally can only control the window covering to roll up and fall down between a up limit point and a down limit point, but in practical using processes, especially in some special conditions, for avoid potential safety hazards, such as in conditions of the rising and falling of a car window covering, or the rising and failing of a control room window covering, a certain position point (we call this point as the critical point of safety position) need to be set between said up limit point and said down limit point to stop the motor; if the rising and falling of these window coverings are not limited, it may lead to the rising up or falling down of the window covering, once the control button is triggered by incorrect manipulation, which will block the view of the operator, and will lead to the occurring of safety accidents.